Over the final decades of the twentieth and the first decade of the twenty-first centuries, the unpredictable and finite nature of non-renewable fossil fuel supplies has become increasingly apparent. Ironically, this realization has come at the precise moment when the industrialized nations of the world are demanding engines with greater power output, increased service life, and improved flexibility for automotive, military, aeronautical, and other applications. With more and more nations achieving industrialization, skyrocketing demand and fierce competition for dwindling fossil fuel resources, coupled with greater operational performance requirements, have forced engine designers and manufacturers to consider and pursue alternatives to the inefficient, reciprocating piston, rotating crankshaft, internal combustion engines that have dominated the industry for nearly a century. Presently available alternatives to engines such as hybrid and so-called “green” fuel engines are in their infancy and are unlikely to garner widespread appeal and applicability in the near future. The reasons for this are varied, but include the complexity and expense of these new technologies, the lack of widespread availability of alternative fuels, incompatibility of most alternative fuels with traditional reciprocating engines, and the reluctance of industrialized consumers and industries to sacrifice the power, speed, and reliability of modern reciprocating engines for the, at present, dubious promise of improved fuel efficiency and reduced greenhouse gas emissions.
Historically, one alternative to the conventional, reciprocating piston, rotating crankshaft engine has been the rotary internal combustion engine. Compared to the traditional, reciprocating piston engine in which a crankshaft is rotationally driven by reciprocal motion of pistons, the simplest, earliest rotary engines, with their stationary crankshafts and rotating cylinder/piston blocks, achieved higher power-to-weight ratios, were simpler to construct and maintain, had fewer moving parts, had a decreased risk of engine seizure, and experienced lower operational vibration compared to reciprocating, internal combustion engines. The advantages of early, stationary crankshaft, rotating block rotary engines, in which the rotational motion of the cylinder block circumferentially about a stationary crankshaft is still produced via gas pistons, have been common knowledge for almost a century. In fact, rotary-styled, internal combustion engines employing rotating cylinder blocks and pistons were one of the most popular aircraft engine designs in the first quarter of the twentieth century, being employed in more than half of all World War I aircraft. Such engines have seen limited application in automobiles and motorcycles. However, these stationary crankshaft, rotating block rotary engines have historically not proven any more fuel efficient than conventional reciprocating engines and are still plagued with many of the same shortcomings, including high mechanical stresses due to rapid, constant acceleration and deceleration of the cylinder pistons, seal leakage, high unit weight, and overall poor operational efficiencies. Additionally, gyroscopic effects generated by the inertia of the rotating block and the inherent difficulties in controlling engine speed, forced engine designers to concentrate their efforts on improving the operational characteristics of the traditional, reciprocating piston engines by the mid 1920s.
Another alternative to the reciprocating piston engine, the pistonless, rotary internal combustion engine, in which a rotor is used rather than pistons, has the potential for even higher power-to-weight ratios and greater fuel efficiency than rotating block, stationary crankshaft rotary engines. These engines also have the potential for longer operational life due to the virtual elimination of the high mechanical stresses caused by the constant, rapid acceleration and deceleration of the pistons, cylinders, and associated parts in the piston-driven, reciprocating and rotating block, stationary crankshaft rotary engines. Additionally, the elimination of moving cylinders, pistons, and associated hardware render the pistonless, rotary internal combustion engine lighter, more reliable, and far less prone to catastrophic mechanical failure than either the reciprocating or rotating block rotary engines, although maintaining seal integrity becomes difficult as the rotor and housing experience mechanical wear. When new, however, this minimization of moving parts and the very low friction between the rotational and fixed/stationary units significantly increases engine efficiency because less energy is lost to frictional heat generation. In turn, the reduced heat generation in the pistonless, rotary engine translates into reduced reliance on complex cooling systems when compared to conventional, reciprocating and rotating block, stationary crankshaft rotary engines. However, despite the high power-to-weight ratio and other potential benefits, the few existing, modern, pistonless, rotary engines, such as the Wankel engine introduced in the 1960s, in which the rotor assembly is eccentrically rotated about a fixed crankshaft without the aid of gas pistons, are heavily criticized for poor fuel efficiency, incomplete combustion of the air-fuel mixture, high hydrocarbon emissions, inability to effectively couple multiple stages or rotor assemblies together without complex bearing mechanisms, and poor rotor gas seals caused by the mechanical wear of the three-sided, eccentric rotor assembly and the engine housing.
Presently, no engine design exists that addresses the shortcomings of the stationary crankshaft, rotating block, rotary internal combustion or the pistonless, Wankel-styled engines. Considering the aforementioned potential advantages of a pistonless, rotary internal combustion engine over traditional reciprocating and rotating block, stationary crankshaft rotary engines in terms of power-to-weight ratios, fuel efficiency, simplicity of construction, reduced maintenance, and lower operational vibration, what is urgently needed is a pistonless, low friction, rotary engine (as well as relatively simple systems for venting exhaust gases and supplying cooling, lubrication, electrical power, fuel, and air to the engine) that provides for more complete fuel-air mixture combustion, greater seal integrity, higher power-to-weight ratios, and increased fuel efficiency than the presently available, reciprocating, rotating block, rotary, or pistonless, Wankel-styled internal combustion engines. Such a solution should be readily adaptable to operation using regular or alternative fuels, such as hydrogen, renewable biofuels, methane, and the like, without sacrificing the engine power and convenience to which the contemporary consumer has become accustomed. Additionally, such a solution could be easily configurable and/or modular, for example, stackable where multiple stages or rotors could be coupled together end-to-end to meet virtually any consumer/operational power requirement. Ideally, a solution could utilize a controlled release (or “bleed off”) system for combustion gases to even further reduce engine vibration caused by combustion of the fuel-air mixture and the concussion of exhaust gases. Additionally, such a solution should permit engine cooling to be by means of forced air, liquid coolants, or some combination of both.